This application claims the benefit of Korean Patent Application No. 1999-47296, filed on Oct. 28, 1999, which is hereby incorporated by reference for all purposes as if fully set forth herein.
1. Field of the Invention
This invention relates to a technique for preventing a defect caused by static electricity in a process of fabricating a substrate of a liquid crystal display, and more particularly a method of fabricating a liquid crystal display wherein gate metal film patterns are connected to each other by a connecting pattern, and thereafter the connection of the gate metal film is separated when a data metal film pattern and/or an indium tin oxide (ITO) film pattern are formed so as to prevent an insulation breakage of a gate insulating film caused by a static electricity in a process of depositing the gate insulating film.
2. Description of the Related Art
Generally, as shown in FIG. 1, a liquid crystal display (LCD) has thin film transistors (TFT""s) 25 arranged at each intersection between gate bus lines 20 and data bus lines 30. Each of pixel electrodes 40 provided at an area surrounded by a gate bus line 20 and a data bus line 30 is connected to each output terminal a corresponding one of the TFT""s 25. A gate driver 21 for driving the gate bus lines 20 is connected to the ends of the gate bus lines 20, and a data driver 31 for driving the data bus lines 30 is connected to the ends of the data bus lines 30.
The gate driver 21 and the data driver 31 have employed a structure in which devices such as TFT""s are provided at the peripheral of a pixel array of the substrate in accordance with a development of an integrated circuit technique. FIG. 2 shows an example of the conventional driver circuit for driving one line. In FIG. 2, the driver circuit is configured by a serial and parallel combination of six TFT""s. Herein, a is a terminal connected to one gate line, and b1, b2, b3 and b4 are connecting terminals of the driver circuit.
FIG. 4 is a plan view showing an exemplary structure of a conventional LCD substrate including the driver circuit. The LCD substrate includes a pixel array provided with gate bus lines 20, data bus lines 30, pixel electrodes 40 and TFT""s 25, and a driver circuit 16. In FIG. 4, a reference numeral 17 represents a gate start lead line.
Hereinafter, a process of fabricating the conventional LCD substrate will be described in detail with reference to FIG. 3, FIG. 5 and FIG. 6. FIG. 5 and FIG. 6 are section views of the LCD substrate taken along the I-Ixe2x80x2 line and the II-IIxe2x80x2 line in FIG. 4, respectively.
First, a buffer layer is provided on a transparent substrate 1 and an amorphous silicon (a-Si) layer is formed into a land-shaped pattern on the buffer layer 2 to provide a semiconductor layer 3. In turn, a first insulating film 4 made from SiNx or SiOx and a gate metal film 5 made from Cr, Mo or Al are sequentially disposed and then patterned into the same pattern shape. A gate electrode 20a constituting a portion of the gate metal film is formed into a narrower width than the land-shaped semiconductor layer 3 at a portion where TFT is formed by way of the first insulating film 4 on the semiconductor layer 3. Particularly, the pattern of the gate metal film 5 is formed in such a manner that the array gate bus line 20, the gate electrode 20a, the driver gate bus line 42, the gate start lead line 17 are separated from each other. Next, an ohmic contact layer is formed by doping each side surface of the semiconductor layer with impurity ions using the patterned gate metal film 5 as a mask.
Subsequently, a second insulating film 7 made from SiNx or SiOx is deposited as shown in FIG. 7A. Since the gate metal film 5 constituting the gate electrode 2a, etc. has been floated in a deposition process of the second insulating film 7 and exposed to a plasma in a deposition equipment, a potential difference caused by a static electricity is generated at the separated gate metal film 5, that is, between the array gate bus line 20 and the driver gate bus line 42. Thus, an insulation breakage may be caused on the second insulating film 4 to form a gap 50 in the second insulating film 7.
If a first contact hole 11 for exposing each side surface of the semiconductor layer 3 is formed in the second insulating film 7 in such a state that the gap 50 has been formed in the second insulating film 7 as mentioned above, then an etchant is penetrated through the gap 50 to damage the gate metal film 5. Also, if the data metal film 43 is formed on the second insulating film 7, then a short may be generated between the gate metal film 5 and the data metal film 43 through the 50.
Subsequently, the data metal film 43 is formed into a desired pattern to provide data bus lines 30, source electrodes 30a and a data metal film 8 of the driver. By the pattern formation of the data metal film 43, the TFT""s 25 are provided at the pixel array 15 and the driver circuit 16 of the LCD substrate.
Finally, a third insulating film 9 made from an inorganic insulating material5 such as SiNx or SiOx or an organic insulating material such as polyimide is deposited and a second contact hole 12 is formed to expose a partial surface of the drain electrode 30b of the TFT included in the pixel array. Thereafter, an ITO film is provided at the entire surface of the third insulating film 9 and then patterned to form the pixel electrode 40 of the pixel array.
As described above, the edge of the LCD substrate provided with the driver circuit has such a structure that the TFT""s are arranged as shown in FIG. 6 and then the third protective film 9 is provided to cover the TFT""s, whereas the pixel array thereof has such a structure that the TFT""s are arranged as shown in FIG. 5 and then the pixel electrodes 40 contacting the drain electrodes of the TFT""s are provided.
Accordingly, the present invention is directed to a liquid crystal display device and method of fabricating the same that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention to provide a method of fabricating a liquid crystal display device that is adapted for preventing an insulation breakage of an insulating film caused by a static electricity.
A further object of the present invention is to provide a method of fabricating a liquid crystal display device that is adapted for preventing a short between a gate metal film and a data metal film caused by an insulation breakage of an insulating film.
A still further object of the present invention is to provide a method of fabricating a liquid crystal display device that is adaptive for preventing a damage of a gate metal film caused by an insulation breakage of an insulating film.
A still further object of the present invention is to provide a method of fabricating a liquid crystal display device that is adaptive for preventing an insulation breakage of an insulating film as well as improving a fabrication yield of a liquid crystal display device without any additional mask process.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, a liquid crystal display device according to one aspect of the present invention includes a gate metal film formed at the center of a semiconductor layer with being interleaved with a first insulating film; a connecting metal film connected to the gate metal film and formed at a substrate; a second insulating film covering the gate metal film and the connecting metal film and provided with a first contact hole to expose a part of each side surface of the semiconductor layer and the center portion of the connecting metal film; a data metal film provided on the second insulating film contacting the semiconductor layer by way of the first contact hole formed in each side surface of the semiconductor layer; a third insulating film covering the data metal film and the second insulating film and provided with a second contact hole to expose a part of the data metal film and the center portion of the connecting metal film; and a pixel electrode provided on the third insulating film by way of the second contact hole, said connection parts exposed by the first and second contact holes being separated from each other.
A method of fabricating a liquid crystal display device according to another aspect of the present invention includes the steps of patterning a first metal film to form a gate metal film and a connecting metal film for connecting the gate metal film; forming an insulating film to cover the gate metal film and the connecting metal film, and forming a first contact hole in the insulating film to expose at least one surface of the connecting metal film; forming a second metal film on the insulating film provided with the first contact hole, and patterning the second metal film to provide a data metal film and, at the same time, to etch and primarily separate the connecting metal film by an etchant for the data metal film; forming a protective insulating film on the data metal film, and forming a second contact hole on the protective insulating film to expose a partial surface of the data metal film and the separated area of the connecting metal film, and forming a third metal film on the protective insulating film provided with the second contact hole, and patterning the third metal film to provide a pixel electrode connected to the data metal film and, at the same time, to secondarily separate the separated part of the connecting metal film by an etchant for the pixel electrode.
A method of fabricating a liquid crystal display device according to still another aspect of the present invention includes the steps of forming a land-shaped semiconductor layer on a substrate; disposing a first insulating film and a first metal film on the substrate provided with the semiconductor layer, and patterning the first insulating film and the first metal film into almost identical shape to provide a connecting metal film for connecting the first metal film to the gate metal film in such a manner that at least part of the gate metal film is interleaved with the first insulating film to be overlapped with the center portion of the semiconductor layer; doping each side surface of the semiconductor layer with impurity ions using the gate metal film and the connecting metal film as a mask; forming a second insulating film on the substrate in which the semiconductor layer is doped with the impurity ions; forming a first contact hole in the second insulating film to expose each side surface of the semiconductor layer doped with the impurity ions and a partial surface of the connecting metal film; forming a second metal film on the substrate provided with the first contact hole and then etching the same to form a pattern of the data metal film contacting the semiconductor layer doped with the ions and, at the same time, etching the exposed part of the connecting metal film to separate the connecting metal film; forming a third insulating film on the substrate in which the connecting metal film has been separated, and forming a second contact hole in the third insulating film at a part of the data metal film and the separated area of the connecting metal film; and forming a third metal film on the third insulating film provided with the second contact hole and then etching the same to provide a pattern of the pixel electrode contacting a part of the data metal film, and making an additional etching of the separated connecting metal film.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.